The sounder module is an important acoustical component of the portable electronic device, is used for transforming electrical signal to acoustical signal, and is an energy converter. The existing sounder module typically comprises a housing in which a vibration system and a magnetic circuit system are accommodated. The housing is provided with a sound hole at the position opposite to the vibration system. The sound hole is formed to be opposite to the centre position of the vibration system, and the end part of the sound hole is flush with the outer surface of the housing. However, in some sounder modules, in order to meet the requirement on structure design of the integrated system, a protruded upper sound hole is typically provided, that is, the channel of the sounding hole is relatively longer, and its end part is higher than the outer surface of the housing. At the same time, in order to meet the requirement on system assembly, the sound hole cannot be provided at the center position of the vibration system. Such an asymmetric rising opening of the sound hole will cause the asymmetrical sound field distribution of a front acoustic cavity of the sounder module. The sound pressure is released largely at the sound hole, and thus the sound field energy is more concentrated at the sound hole. The region with relatively concentrated sound field energy will cause larger reaction force to the vibrating system, resulting in the asymmetrical sound pressure distribution on the surface of the vibrating diaphragm, as shown in FIG. 5. The asymmetric arrangement of the sound hole will lead to the asymmetrical sound loading force distribution on the surface of the vibrating diaphragm, which will directly lead to aggravated polarization of the vibration system, and increased harmonic distortion.